Herbert h



HERBERT H. DOW, OF MIDLAND, MICHIGAN, ASSIGNOR TO THE DOW CHEMICALCOMPANY, OF MIDLAND, MICHIGAN, A. CORPORATION OF MICHIGAN.

RECOVERY OF COAL-DISTILLATION PRODUCTS.

No Drawing.

To all whom itmay concern:

Be it known that I, HERBERT H. Dow, a

citizen of the United States, and a resident of Midland, county ofMidland, and State of Michigan, have invented a new and usefulImprovement in the Recovery of Coal- Distillation Products, of which thefollowing is aspecification, the principle of the invention being hereinexplained and the best mode in which I have contemplated applying thatprinciple, so as to distinguish it from other inventions.

In the destructive distillation of coal, one of the main fractions ofthe by-products recovered from the distillation process is the so-calledfirst light oil, which is the fraction distilling at a temperature up to170 degrees centigrade. This fraction is made up of benzene, toluene andhigher homologues, with phenol, cresol, naphthalene, etc. The productsobtained from it are then separated by redistilling the whole fractionin a small still of the same general type as the large tar still fromwhich the main fraction is derived. By this redistillation such firstlight oil is ordinarily separated into three sub-fractions, the first ofwhich constitutes the so-called 90% benzol which is the product comingover at temperatures up to 110 degrees centigrade. The actual percentagecomposition of the 90% benzol of good quality isabout 70% benzene, 24%toluene, including a little xylene, and 4 to 6% of carbon bisulfid andlight hydrocarbons.

The present improved process is more particularly concerned with thetreatment of such carbon bisulfid and light hydrocarbons, theseheretofore having been found inseparable because of their havingapproximately the same boiling point, and so' far as ll am aware, nomethod has heretofore been practised for making any economical use ofsuch products, despite their obviously valuable character, particularlythat of carbon bisulfid.

With this object in View, the present invention then consists of thesteps hereinafter fully described and particularly pointed out in theclaims, it being understood that the following description disclosesonly one of various ways in which the principle of the invention may becarried out.

As indicated above, the principal light Specification of Letters Patent.

Application filed January 14, 1918.

Patented Sept. 30 1919.

Serial No. 211,726.

hydrocarbon which remains associated with the carbon bisulfid after the.redistillation of the high fractions of the benzol, I have foundispentane (0 1E1 which has a boiling point of from 37 to 89 degs.centigrade. The boiling point of carbon bisulfid being around 46 degs.centigrade, it will be seen that the separation of these twoconstituents by the ordinary process of fractional distillation would be,a very tedious one if possible at all.

I have discovered, however, that it is perfectly feasible to convertthis light hydrocarbon into a substitution product having a veryconsiderably higher boiling point than carbon bisulfid, by treating themix-. ture with a halogen, z'. e., chlorin or bromin, or both, in thepresence of a suitable catalytic agent such as iron. The result of suchtreatment where chlorin is used is presumably the formation of pentylchlorid (0 11 01), at least in part, which has a boiling point ofapproximately 160- degs. centigrade.

Such treatment with chlorin or bromin, however, does not affect in anyway the carbon bisulfid (CS so that such bisulfid may be readilyseparated from the resulting mixture of the bisulfid with thehalogenated pentane or other light hydrocarbon, by the familiar processof fractional distillation. In this way, not only is the valuable carbonbisulfid segregated by the halogenated hydrocarbon likewise constitutesa valuable product, being available for various uses in the arts.

Other modes of applying the principle of my invention may be employedinstead of the one explained, change being made as regards the processherein disclosed, provided the step or steps stated by any one of thefollowing claims or the equivalent of such stated step or steps beemployed.

I therefore particularly point out and distinctly claim as myinvention 1. In the recovery of coal-distillation products, the stepswhich consist in segregating the fraction which contains pentane andcarbon bisulfid, these constitutents having approximately the sameboiling point, and then treating such fraction with a halogen, wherebysuch pentane is converted into a product having a higher boiling pointthan,

and so separable from, such carbon bisulfid.

2. In the recovery of coal-distillation separable from, such carbonbisulfid.

3. In the recovery of coal-distillation products, the steps whichconsist in segregating from the first light oil the sub-fraction whichcontains pentane and carbon bisulfid, these constitutents havingapproximately the same boiling point, and then chlorinating such entane,whereby it is converted into a pro not having a higher boil-' ing'pointthan, and so separable from, such carbon bisulfid.

4. In the recovery of coal-distillation products, the steps whichconsist in segre gating from the first light oil the sub-fraction whichcontains pentane and carbon bisulfid, these constitutents havingapproximately the same boiling point, and then treating such pentanewlth chlorin in the presence of iron, whereby it is converted into aproduct having a lngher boiling point than, and so separable from, suchcarbon 5. In the recovery of coal-distillation products, the steps whichconsist in segregating from the first light oil the sub-fraction whichcontains pentane and carbon bisulfid, these constitutents havingapproximately the same boiling point, and then halogenating suchpentane, whereby it is converted into a product having a higher boilingpoint than, and so separable from, such carbon bisulfid.

6. In the recovery of coaldistillation products, the steps which consistin segregating from the first light oil the sub-fraction which containspentane and carbon bisulfid, these constitutents having approximatelythe same boiling point, and then converting such pentane into a producthaving'a dif ferent boiling point than, and so separable from, suchcarbon bisulfid.

Signed by me this 9th day of January, 1918.

HERBERT H. DOW; v

